1. Field of the Invention
The present invention relates generally to a vehicular lamp, and more particularly to a vehicular lamp which is improved in a structure of electrical connection between a lamp bulb serving as a light source installed in a lamp body and an external power source for supplying electric power to the lamp bulb.
2. Related Art
According to a conventional structure for electrically connecting with a lamp bulb installed in a lamp body of a vehicular lamp, a power source code is connected through connection codes with both a bulb code on a positive side connecting to a metal piece of the lamp bulb and an earth code on a negative side (earth side). Particularly in a case where the lamp bulb is installed within the lamp body in such a manner that an aiming adjustment can be performed, since a reflector and the lamp bulb are operated to pivotally move relative to the lamp body, the bulb code and the earth code are connected with a relay connector which electrically connects with the outside of the lamp body in order to prevent these codes from obstructing the pivotally movement.
FIG. 14 is a perspective view, showing one example of the conventional electrical connection structure. As shown in FIG. 1-4, a bulb insertion hole 8 is formed in a back surface of a lamp body 1 and a lamp bulb 5 is detachably mounted through the bulb insertion hole 8 on a reflector 3 which is installed within the lamp body 1. A back cover 9A for covering the bulb insertion hole 8 is fitted in the bulb insertion hole 8 to seal the inside of the lamp body. The back cover 9A is provided with a relay connector 40 and a pair of electrode pieces 41 supported at the inner side thereof. An electrode terminal disposed at a tip end of a bulb code 22 of a positive side connecting with the lamp bulb 5 engages with the electrode piece 41 of the relay connector 40 so that the electrical connection is achieved.
An intermediate code 42 drawn out of the back cover 9A has one end part connecting with the other end of the electrode piece 41 of the relay connector 40 and the other end part connecting with an intermediate connector 43. The intermediate connector 43 engages with a vehicle side connector 44 connecting with a power supply code 29. When the intermediate connector 43 engages with to the vehicle side connector 44, electric power is supplied from a battery mounted on a vehicle body to the lamp bulb 5 through the power supply code 29, vehicle side connector 44, intermediate connector 43, intermediate code 42 and relay connector 40. An earth code 30 having one end part connecting directly with the intermediate connector 43 is provided with an earth electrode terminal 31 disposed at the other end part thereof engaging electrically with an earth terminal disposed on the reflector.
By using the relay connector 40, even in a case where external force is applied between the power supply code 29 and the intermediate code 42, the external force is absorbed by the relay connector 40 and not applied up to the bulb code 22, so that the bulb code 22 would not be broken or the lamp bulb 5 would not be damaged due to unnatural force applied thereto. Further, by disposing the intermediate connector 43 and the vehicle side connector 44, the workability for attaching /detaching operation of the lamp to and from the vehicle body can be improved.
However, the conventional structure as described above is suffered from a problem that it requires the relay connector 40 disposed on the back cover 9A, the intermediate connector 43 and the vehicle side connector 44 for connecting the relay connector 40 with the power supply source, which raises the number of parts.
Further, when the lamp bulb 5 is attached or detached during maintenance or the lamp bulb 5 is exchanged, the conventional structure requires an operation for engaging the intermediate connector 43 with the vehicle side connector 44, an operation for connecting the intermediate code 42 with the relay connector 40, in addition, an operation for connecting the bulb code 22 with the relay connector 40 and an operation for attaching or detaching the earth electrode terminal 31 of the earth code 30 to or from the earth terminal. Therefore, many operation steps are required so that the workability during assembly is complicated and ineffective.
Furthermore, as described above, if an external force such as purring force is applied to the intermediate code 42 through the power supply code 29 drawn out of the lamp, the external force is prevented from applying to the lamp bulb 5 owing to the intermediate connector 40. However, the external force may cause a damage to the relay connector 40 because a wire break may occur at a connection point between the intermediate code 42 and the relay connector 40, for example, a connection point between the electrode pieces 41 and the intermediate code 42. If such a wire breaks occurs, the repair would be intricate because it is within the back cover 9A.